Poor Ralph Bellamy. He's a nice, well-intentioned guy who could probably make some woman happy, if given half the chance. But Bellamy is the archetypal example of "The Baxter," a character who exists solely as a speed bump in another couple's inevitable union. The heroine will toy with him for a while, considering the life of bland stability he has to offer, but ultimately, Bellamy is too much of a square and not nearly smart or witty enough to keep up with her. As a rich-but-bland Oklahoma oil-man in The Awful Truth and a sweet-but-bland lump from Albany in His Girl Friday, Bellamy tries to romance the fast-talking, glamorous likes of Irene Dunne and Rosalind Russell away from the impossibly suave Cary Grant. Good luck with that one, chum.

2. Ernest Borgnine & Bette Davis, The Catered Affair (1956)

Just like the pop stars of the '40s dealt with the arrival of rock 'n' roll a decade later, movie stars from Hollywood's golden age struggled to keep up in an era of mumbly Method acting. In the year that Marty won Best Picture, Bette Davis jumped on the Paddy Chayefsky/Ernest Borgnine bandwagon for The Catered Affair, in which she plays the wife of Bronx cabbie Borgnine, straining to find money for the wedding of daughter Debbie Reynolds. The movie itself is sweet, filled with the kind of knowing working-class detail that Chayefsky brought with him from the New York theater. But it's hard to get past Davis' attempts to match every one of Borgnine's dropped Gs and guttural grunts. She delivers lines like "You're gonna have a nice weddin'!" like she learned them phonetically.

3. Al Pacino & Chris Sarandon, Dog Day Afternoon (1975)

Sidney Lumet's based-on-a-true-story heist-gone-wrong film Dog Day Afternoon is a masterpiece, by turns taut, hilarious, and humanistic, and just a blast to watch. The one aspect that doesn't quite work? The central relationship between two characters who never actually appear onscreen together. Al Pacino is a manic, none-too-bright would-be bank robber who wants the money to buy a sex change for his lover, Chris Sarandon. Sarandon is a weary, bathrobe-sporting, wrist-lolling queen, hauled out of Bellevue by the cops to talk some sense into his man. The script called for a face-to-face scene, complete with a kiss, but Pacino refused, and their phone exchange never particularly sells them as a couple, let alone one whose relationship would inspire Pacino to such passion. They're both fine characters on their own (though Sarandon's tragic-camp routine is a bit overplayed), but that's as far as it goes.

4. John Travolta & Lily Tomlin, Moment By Moment (1978)

In the late '70s, John Travolta was looking to break out of dreamboat roles and be taken seriously as a dramatic actor. So a star-crossed romantic drama pairing Travolta with the legendary Lily Tomlin must have seemed like a good idea. Alas, the surreal disconnect between Travolta's Noo Yawk working-class charm and Tomlin's spinsterish gravity made the resulting film, Moment By Moment, a historic flop, and the Tomlin-Travolta teaming one of cinema's most egregious mismatches. Clearly, being miscast as John Travolta's love interest must be the single most traumatic thing that's ever happened to Tomlin on a movie set. Or maybe not.

5. Woody Allen & Juliette Lewis, Husbands And Wives (1992)

Woody Allen has become notorious for casting himself in onscreen couplings with beautiful young women decades his junior: Julia Roberts in Everyone Says I Love You, Elisabeth Shue in Deconstructing Harry, Debra Messing in Hollywood Ending. Though the age difference between Allen and Juliette Lewis in Husbands And Wives is especially pronounced—Allen was 57, Lewis 19—the autobiographical nature of the film gives the extramarital relationship a perfectly good rationale. And yet the two look ridiculous together anyway, mainly because Lewis, extending the airy girlishness of her breakthrough role in Cape Fear, can't get her gums around Allen's hyper-literate dialogue. The combination of Lewis pronouncing words as if reading from cue cards and Allen courting her at her parents' house makes for some creepy viewing, which is likely the point.

6. Sean Connery & Lorraine Bracco, Medicine Man (1992)

John McTiernan's South American eco-adventure Medicine Man pairs Sean Connery (as a rogue pharmaceutical-research scientist) with Goodfellas starlet Lorraine Bracco (as the company woman sent to bring this ersatz Kurtz home). Originally, the movie was going to be anchored by an African Queen-like romance between the gruff naturalist Connery and the fussy intellectual Bracco. But Bracco's whiny, one-note performance made the prospect of a torrid affair between the characters seem ridiculous, and many of the love scenes were cut. Amazingly, the movie sticks with its original ending. Bracco bids farewell to her boyfriend back home—in an hilariously awful voiceover—to live out her life with a man she's barely even kissed.

7. James Woods & Dolly Parton, Straight Talk (1992)

Dolly Parton boasts such a larger-than-life persona that her leading men need to be equally larger-than-life just to avoid being blown offscreen. Best Little Whorehouse In Texas co-star Burt Reynolds and Rhinestone songbird Sylvester Stallone fit the bill, with their massive physiques and equally gaudy levels of testosterone. Straight Talk co-star James Woods, meanwhile, boasts a mercurial presence that, while creepily intense, somehow failed to gel with Parton's down-home, aw-shucks affability. Consequently, the teaming of Woods and Parton failed to live up to the standards set by Sandler and Barrymore, let alone Tracy and Hepburn or Bogey and Bacall.

8. Nick Nolte & Julia Roberts, I Love Trouble (1994)

One of the reasons why Julia Roberts never landed in the romantic-comedy ghetto with so many of her peers is because the prickly, moody characters she prefers don't match up well with conventional leading men. So give credit to Nancy Myers and Charles Shyer for having the gumption to try throwing Roberts up against growly old Nick Nolte in the throwback newspaper comedy I Love Trouble. Roberts plays a scoop-happy beat reporter—which in itself seems like kind of a stretch—who rankles her cross-town rival Nolte by beating him to crime scenes. But with his mush-mouthed line deliveries and fidgety gestures, Nolte isn't exactly the go-to guy for witty repartee. When the flinty Roberts goes all moony for him, it's about as plausible as a coat rack falling in love with a grizzly bear.

9. Harrison Ford & Anne Heche, Six Days Seven Nights (1998)

It didn't help the commercial prospects of the slight-but-enjoyable castaway romance Six Days Seven Nights when Anne Heche became publicly involved with America's most famous lesbian, Ellen DeGeneres, shortly before the film's release. But if audiences had a problem buying Heche as a high-powered magazine editor who falls for rough-hewn pilot Harrison Ford, it wasn't really Heche's fault; she played the flustered professional woman with élan. Instead, blame Ford, well into the "sullen grouch" phase of his acting career. Ford smiles occasionally while escorting Heche through a pirate-infested jungle, but mostly, he sweats, grumbles, and slings sarcasm. It's enough to make any woman swear off men.

10. Jimmy Fallon & Drew Barrymore, Fever Pitch (2005)

There's no question that Drew Barrymore knows her way around a romantic comedy, but her male counterpart needs to serve as a grounding force, someone solid to offset her flower-child mannerisms and halting rhythms of speech. What she doesn't need is Jimmy Fallon, who basically does the same awkward shtick, except he's not nearly as seasoned as Barrymore, and he's several times as self-satisfied. Together, they're like two north ends of a magnet trying desperately to force themselves together, and not even an improbable Boston Red Sox World Series victory can make their relationship stick.

11. Joseph Gordon-Levitt & Mo'Nique, Shadowboxer (2005)

Any film that casts Cuba Gooding, Jr. as Helen Mirren's stepson/lover/partner in contract killing has some serious casting issues from the start. Astonishingly, the film boasts an even more incongruous mismatch in the pairing of the slight, intense young thespian Joseph Gordon-Levitt with plus-sized sass-master and Domino cut-up Mo'Nique. It's hard to say which is harder to buy: Gordon-Levitt—fresh off playing a high-school gumshoe in Brick—as a doctor, or him and Mo'Nique as an item.

12. Ben Affleck and Jennifer Lopez, Gigli (2003)

It's generally accepted that offscreen romance rarely translates into onscreen chemistry. But it's rare that the chemistry fizzles quite so spectacularly as it did with Affleck and Lopez in Martin Brest's ill-starred, Baywatch-referencing kidnap comedy. Affleck seems fully committed to his part as a mob thug forced to get in touch with his feminine side, so the blame falls pretty squarely on Lopez, who by that point had seemingly decided that acclaimed turns in Selena and Out Of Sight meant she only had to show up and smile. Her Gigli character is a lesbian, but that seems like the least of Bennifer's impediments as an onscreen couple. Lopez's waiting-for-the-director-to-say-"cut" look is a much bigger problem.

13. Charles Grodin & Miss Piggy, The Great Muppet Caper (1981)

Boy meets pig. Boy frames pig as a jewel thief. Boy loses pig, and has all his leather-clad supermodel/cat-burglar sidekicks karate-chopped into submission by pig. It's practically the world's oldest story. But is the boy really feeling it? Probably not. While Charles Grodin does romance Miss Piggy during The Great Muppet Caper, even singing her a heartfelt love song, complete with a Esther Williams-satirizing synchronized-swim routine, he never really sells the lines "When does the rapture begin and grow / Where does devotion and passion go / All the world's ever wanted was you, a dream come true." Maybe it's just that Grodin usually plays his roles in a removed, condescending sort of way, and he just wasn't cut out for a love story. Or, well Not to be shallow and prejudiced, but maybe they just aren't convincing as a couple because she's half his height, the wrong species, and made out of felt.